In portable handheld work apparatus driven by an internal combustion engine, the hot exhaust gases of the engine are guided through an exhaust-gas muffler. Such work apparatus include chain saws, brushcutters, suction/blower apparatus or the like. The exhaust-gas muffler assumes considerable temperatures. An exhaust-gas catalytic converter, which is possibly integrated into the exhaust-gas system, brings about an after burning of incompletely combusted exhaust-gas components. A considerable increase of the temperature level in the exhaust-gas system can, under circumstances, take place because of the after burning in the exhaust-gas catalytic converter.
An exhaust-gas muffler, which is equipped with an exhaust-gas catalytic converter as needed, is affixed to any desired apparatus part of the portable handheld work apparatus with one or several attachment pins. The attachment pins can be configured as threaded fasteners, stud bolts or the like and are especially subjected to mechanical vibration loads as well as thermal loads. The attachment pins define a thermal bridge between the exhaust-gas muffler which is hot during operation and the comparatively cooler apparatus part. Temperature fluctuations in the exhaust-gas muffler, for example, because of frequently changing power outputs or starting and stopping of the engine can lead to a loosening of the attachment pins especially in combination with vibration loads resulting from the engine operation. When the apparatus part, which receives the attachment pins, is configured of a light metal, especially magnesium or a corresponding plastic material, a high heat entry via the attachment pin can lead to a creeping of the material of the apparatus in the region of the attachment pin. The creeping of the material receiving the attachment pin can, likewise, lead to an unwanted automatic loosening of the exhaust-gas muffler attachment.
For a reliable attachment of an exhaust-gas muffler, configurations of attachment pins are known wherein a comparatively long threaded section is provided at the apparatus end. A relatively large transition surface can be provided for the introduced heat via the long threaded section threadably engaged in the housing part. During operation, a comparatively low temperature level is present on the end of the threaded section facing away from the exhaust-gas muffler. At least in this region, a permanently secure threaded connection can be obtained especially in association with an adhesive.
A sufficient amount of structural space is not always available for accommodating the correspondingly long threaded section. A correspondingly long configuration of the attachment pin can, under certain circumstances, not lead to the desired success especially for a high temperature level caused by an exhaust-gas catalytic converter. An adhesive locking of the threaded fastener leads to a cost intensive assembly operation. Creeping of the material, which accommodates the threaded section, cannot be avoided under some circumstances, at least not in the hotter region of the threaded section.